A way is an ordered list of nodes which normally also has at least one tag or is included within a Relation. A way can have between 2 and 2,000 nodes, although it's possible that faulty ways with zero or a single node exist. A way can be open or closed. A closed way is one whose last node on the way is also the first on that way. A closed way may be interpreted either as a closed polyline, or an area, or both.

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Types of way

Open way

An open way is way describing a linear feature which does not share a first and last node. Many roads, streams and railway lines are open ways. Identifying the direction of a 'way'.

Closed way

A closed way is a way where the last node of the way is shared with the first node with suitable tagging. A closed way that also has a area=yes tag should be interpreted as an area (but the tag is not required most of the time, see section below).

The following closed way would be interpreted as closed polylines:

highway=* Closed ways are used to define roundabouts and circular walks

barrier=* Closed ways are used to define barriers, such as hedges and walls, that go completely round a property.

Area

An area (also polygon) is an enclosed filled area of territory defined as a closed way. Most closed ways are considered to be areas even without an area=yes tag (see above for some exceptions). Examples of areas defined as closed ways include:

The nodes defining the geometry of the way are enumerated in the correct order, and indicated only by reference using their unique identifier. These nodes must have been already defined separately with their coordinates.